Display apparatus and method of driving the same

ABSTRACT

A display apparatus includes a display, a frequency compensator, a frequency adjuster, and a driver. The display includes first, second, and third pixels to display an image having color information. The frequency compensator receives first, second, and third pixel data respectively corresponding to the first, second, and third pixels, converts the first, second, and third pixel data to hue data, and outputs a frequency control signal to change a current driving frequency of the display based on the hue data. The frequency adjuster changes the driving frequency to a predetermined compensation frequency in response to the frequency control signal and changes a frequency of image data and an image control signal such that the display is driven at the predetermined compensation frequency. The driver receives the changed image data and the changed image control signal and drives the display at the predetermined compensation frequency.

This application claims priority to Korean Patent Application No.10-2017-0104986, filed on Aug. 18, 2017, and all the benefits accruingtherefrom under 35 U.S.C. § 119, the content of which in its entirety isherein incorporated by reference.

BACKGROUND 1. Field

Exemplary embodiments of the invention relate to a display apparatus anda method of driving the same. More particularly, exemplary embodimentsof the invention relate to a display apparatus improving a coloruniformity and a method of driving the display apparatus.

2. Description of the Related Art

A liquid crystal display (“LCD”) apparatus forms an electric field in aliquid crystal layer disposed between two substrates to change analignment of liquid crystal molecules and to control a transmittance ofa light incident thereto, thereby displaying an image.

In general, the LCD apparatus uses three primary colors, e.g., red,green, and blue colors, to display a color. Accordingly, an LCD panelincludes unit pixels each including three pixels respectivelycorresponding to the red, green, and blue colors, and the color formedby a combination of the three pixels is displayed as a representativecolor of the unit pixel.

SUMMARY

In recent years, since a liquid crystal display (“LCD”) apparatusemploys a high resolution structure, a structure that reduces a numberof driving chips, and a high-frequency driving structure, a time desiredto drive each pixel is reduced, and as a result, a charge rate of eachpixel is reduced. A reduction of the charge rate of the pixels causes anon-uniformity in color of the image displayed through the LCDapparatus.

Exemplary embodiments of the invention provide a display apparatuscapable of improving a color non-uniformity caused by a reduction ofcharge rate.

Exemplary embodiments of the invention provide a method of driving thedisplay apparatus.

Exemplary embodiments of the invention provide a display apparatusincluding a display, a frequency compensator, a frequency adjuster, anda driver.

The display includes first, second, and third pixels to display an imagehaving color information. The frequency compensator receives first,second, and third pixel data respectively corresponding to the first,second, and third pixels, converts the first, second, and third pixeldata to hue data, and outputs a frequency control signal to change acurrent driving frequency of the display based on the hue data. Thefrequency adjuster changes the current driving frequency to apredetermined compensation frequency in response to the frequencycontrol signal and changes a frequency of image data and an imagecontrol signal to output the changed image data and the changed imagecontrol signal such that the display is driven at the predeterminedcompensation frequency. The driver receives the changed image data andthe changed image control signal and drives the display at thepredetermined compensation frequency.

Exemplary embodiments of the invention provide a method of driving adisplay apparatus, which includes a display including first, second, andthird pixels to display an image having color information, includingreceiving first, second, and third pixel data respectively correspondingto the first, second, and third pixels to convert the first, second, andthird data to hue data, outputting a frequency control signal to changea current driving frequency of the display based on the hue data,changing the current driving frequency to a predetermined compensationfrequency in response to the frequency control signal, changing afrequency of image data and an image control signal to output thechanged image data and the changed image control signal such that thedisplay is driven at the compensation frequency, and receiving thechanged image data and the changed image control signal to drive thedisplay at the compensation frequency.

According to the above, the hue data are calculated based on the pixeldata including the color information, and the driving frequency ischanged using the hue data when the image having poor color uniformityis driven. Thus, the overall color uniformity of the display apparatusmay be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other advantages of the invention will become readilyapparent by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings, in which:

FIG. 1 is a block diagram showing an exemplary embodiment of a displayapparatus according to the invention;

FIG. 2 is a block diagram showing a frequency compensator shown in FIG.1;

FIG. 3 is a view showing a process of converting first to third pixeldata shown in FIG. 2 to hue data;

FIG. 4 is a view showing a normal driving period and a compensationdriving period;

FIG. 5 is a view showing a transition period between the normal drivingperiod and the compensation driving period;

FIG. 6 is a block diagram showing another exemplary embodiment of adisplay apparatus according to the invention;

FIG. 7 is a block diagram showing an optical characteristic compensatorshown in FIG. 6;

FIG. 8 is a block diagram showing another exemplary embodiment of anoptical characteristic compensator according to the invention;

FIG. 9 is a schematic view showing an exemplary embodiment of a displayapparatus according to the invention; and

FIG. 10 is a schematic view showing another exemplary embodiment of adisplay apparatus according to the invention.

DETAILED DESCRIPTION

The invention may be variously modified and realized in many differentforms, and thus specific embodiments will be exemplified in the drawingsand described in detail hereinbelow. However, the invention should notbe limited to the specific disclosed forms, and be construed to includeall modifications, equivalents, or replacements included in the spiritand scope of the invention.

It will be understood that when an element is referred to as being “on”another element, it can be directly on the other element or interveningelements may be therebetween. In contrast, when an element is referredto as being “directly on” another element, there are no interveningelements present.

It will be understood that, although the terms “first,” “second,”“third” etc. may be used herein to describe various elements,components, regions, layers and/or sections, these elements, components,regions, layers and/or sections should not be limited by these terms.These terms are only used to distinguish one element, component, region,layer or section from another element, component, region, layer orsection. Thus, “a first element,” “component,” “region,” “layer” or“section” discussed below could be termed a second element, component,region, layer or section without departing from the teachings herein.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a,” “an,” and “the” are intended to include the pluralforms, including “at least one,” unless the content clearly indicatesotherwise. “Or” means “and/or.” As used herein, the term “and/or”includes any and all combinations of one or more of the associatedlisted items. It will be further understood that the terms “comprises”and/or “comprising,” or “includes” and/or “including” when used in thisspecification, specify the presence of stated features, regions,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,regions, integers, steps, operations, elements, components, and/orgroups thereof.

Furthermore, relative terms, such as “lower” or “bottom” and “upper” or“top,” may be used herein to describe one element's relationship toanother element as illustrated in the Figures. It will be understoodthat relative terms are intended to encompass different orientations ofthe device in addition to the orientation depicted in the Figures. In anexemplary embodiment, when the device in one of the figures is turnedover, elements described as being on the “lower” side of other elementswould then be oriented on “upper” sides of the other elements. Theexemplary term “lower,” can therefore, encompasses both an orientationof “lower” and “upper,” depending on the particular orientation of thefigure. Similarly, when the device in one of the figures is turned over,elements described as “below” or “beneath” other elements would then beoriented “above” the other elements. The exemplary terms “below” or“beneath” can, therefore, encompass both an orientation of above andbelow.

“About” or “approximately” as used herein is inclusive of the statedvalue and means within an acceptable range of deviation for theparticular value as determined by one of ordinary skill in the art,considering the measurement in question and the error associated withmeasurement of the particular quantity (i.e., the limitations of themeasurement system). For example, “about” can mean within one or morestandard deviations, or within ±30%, 20%, 10%, 5% of the stated value.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and theinvention, and will not be interpreted in an idealized or overly formalsense unless expressly so defined herein.

Exemplary embodiments are described herein with reference to crosssection illustrations that are schematic illustrations of idealizedembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, embodiments described herein should not beconstrued as limited to the particular shapes of regions as illustratedherein but are to include deviations in shapes that result, for example,from manufacturing. In an exemplary embodiment, a region illustrated ordescribed as flat may, typically, have rough and/or nonlinear features.Moreover, sharp angles that are illustrated may be rounded. Thus, theregions illustrated in the figures are schematic in nature and theirshapes are not intended to illustrate the precise shape of a region andare not intended to limit the scope of the claims.

FIG. 1 is a block diagram showing a display apparatus 500 according toan exemplary embodiment of the invention.

Referring to FIG. 1, the display apparatus 500 includes a display 100, afrequency compensator 200, a frequency adjuster 300, and a driver 400.

The display 100 includes a plurality of unit pixels UP. Each of the unitpixels UP includes first, second, and third pixels P(R), P(G), and P(B)and displays an image having color information.

In the illustrated exemplary embodiment, the first, second, and thirdpixels P(R), P(G), and P(B) display one of red, green, and blue colors,and the first, second, and third pixels P(R), P(G), and P(B) displaydifferent colors from each other. However, a kind of colors displayed byeach of the first, second, and third pixels P(R), P(G), and P(B) shouldnot be limited thereto or thereby.

In addition, the number of the pixels included in each of the unitpixels UP should not be limited thereto or thereby. That is, each of theunit pixels UP may include four or more pixels.

The frequency compensator 200 may receive first, second, and third pixeldata R-data, G-data, and B-data respectively corresponding to the first,second, and third pixels P(R), P(G), and P(B). The frequency compensator200 converts the first, second, and third pixel data R-data, G-data, andB-data to hue data H-data (refer to FIG. 2) and outputs a frequencycontrol signal F-con based on the hue data H-data to change a drivingfrequency F1.

In FIG. 1, the frequency compensator 200 receives the first, second, andthird pixel data R-data, G-data, and B-data, but it should not belimited thereto or thereby. In an exemplary embodiment, in a case thatthe unit pixel UP includes four or more pixels, the frequencycompensator 200 may receive four or more pixel data corresponding to thefour or more pixels, respectively, for example.

The frequency adjuster 300 may receive image data Video(F1) and an imagecontrol signal Con(F1), which are desired to drive the display 100, insynchronization with a driving frequency F1.

The frequency control signal F-con output from the frequency compensator200 is applied to the frequency adjuster 300. The frequency controlsignal F-con may include information that determines whether the display100 decreases or increases a currently-driving frequency (hereinafter,referred to as a “driving frequency F1”). In addition, the frequencycontrol signal F-con may further include information on how to set arate of decrease or increase of the driving frequency F1.

The frequency adjuster 300 changes the driving frequency F1 to acompensation frequency F2 based on the information included in thefrequency control signal F-con and converts the image data Video(F1) andthe image control signal Con(F1) to a signal synchronized with thecompensation frequency F2 to output the signal.

Although not shown in FIG. 1, the frequency adjuster 300 may furtherinclude a storing unit to store the compensation frequency F2.Accordingly, the frequency adjuster 300 may recognize the compensationfrequency F2 stored therein as the current-driving frequency of thedisplay 100 in a next frame.

The driver 400 receives the image data Video(F2) and the image controlsignal Con(F2) in synchronization with the compensation frequency F2.The driver 400 outputs data signals D1 to Dm and gate signals G1 to Gnbased on the image data Video(F2) and the image control signal Con(F2)to drive the display 100. Here, n and m are natural numbers. Althoughnot shown in FIG. 1, the driver 400 may include a data driver togenerate the data signals D1 to Dm and a gate driver to generate thegate signals G1 to Gn. In addition, the driver 400 may further include atiming controller to control a drive of the data driver and the gatedriver.

The display 100 receives the data signals D1 to Dm and the gate signalsG1 to Gn to display the image at the compensation frequency F2.

As an example of the invention, the display 100 may be, but not limitedto, a liquid crystal panel including a lower substrate, an uppersubstrate facing the lower substrate, and a liquid crystal layerdisposed between the lower and upper substrates. Although not shown inFIG. 1, the display 100 may further include a plurality of gate linesreceiving the gate signals G1 to Gn and a plurality of data linesreceiving the data signals D1 to Dm.

Each of the first, second, and third pixels P(R), P(G), and P(B) isconnected to a corresponding gate line and a corresponding data line andreceives corresponding gate and data signals to display the image. Therepresentative color of the unit pixel UP may be determined by thecombination of the first, second, and third pixels P(R), P(G), and P(B).

A time desired to drive the unit pixel UP may be shortened depending ona driving method and a pixel arrangement of the display apparatus 500.In this case, a time used to drive each of the first, second, and thirdpixels P(R), P(G), and P(B) is reduced, and as a result, the first,second, and third pixels P(R), P(G), and P(B) may not be sufficientlycharged. Accordingly, since the representative color of the unit pixelUP does not have desired characteristics, the color non-uniformity mayoccur.

In this case, the charge rate of each of the first, second, and thirdpixels P(R), P(G), and P(B) may be compensated by compensating for thedriving frequency used to drive the display 100, i.e., by reducing thefrequency used to drive the display 100. When the charge rate of each ofthe first, second, and third pixels P(R), P(G), and P(B) is compensated,the color non-uniformity caused by an insufficient charge rate may beimproved.

As an example of the invention, each of the first, second, and thirdpixels P(R), P(G), and P(B) shown in FIG. 1 has a structure (i.e., ahorizontal pixel structure) in which a horizontal width is greater thana vertical width. In an exemplary embodiment, the horizontal width ofeach of the first, second, and third pixels P(R), P(G), and P(B) isthree times greater than the vertical width of each of the first,second, and third pixels P(R), P(G), and P(B), for example.

Since each of the first, second, and third pixels P(R), P(G), and P(B)in the horizontal pixel structure is driven during one-third (⅓) of thetime desired to drive one unit pixel, the time desired to charge each ofthe first, second, and third pixels P(R), P(G), and P(B) may be reducedcompared to that of the vertical pixel structure. That is, the colornon-uniformity caused by the reduction of the charge rate may occur inthe horizontal pixel structure. In this case, the occurrence of thecolor non-uniformity caused by the reduction of the charge rate may beprevented by employing the driving frequency compensation method.

The driving frequency compensation method may be applied not only to thedisplay apparatus employing the horizontal pixel structure but also todisplay apparatuses employing the driving method and structure in whichthe charging time of the pixel is reduced to improve the colornon-uniformity.

FIG. 2 is a block diagram showing the frequency compensator 200 shown inFIG. 1, and FIG. 3 is a view showing a process of converting the firstto third pixel data shown in FIG. 2 to the hue data.

Referring to FIG. 2, the frequency compensator 200 includes a converter210, a comparing/determining unit 230, and an outputting unit 250. Theconverter 210 converts the first, second, and third data R-data, G-data,and B-data to the hue data H-data.

Referring to FIG. 3, for the convenience of explanation, the first,second, and third data R-data, G-data, and B-data are represented byvalues from 0 to 1 depending on their grayscale level. In an exemplaryembodiment, in a case that the first, second, and third data R-data,G-data, and B-data are represented by 256 grayscale levels, grayscalevalues from 0 to 255 may be converted to and represented by the valuesfrom 0 to 1, for example. The hue data H-data may be generated based onthe size and ratio of the first, second, and third data R-data, G-data,and B-data.

As an example of the invention, the hue data H-data may include a valuerepresenting a color. The color may be determined by the ratio of thefirst, second, and third data R-data, G-data, and B-data. The hue dataH-data may be divided into red, green, and blue areas RA, GA, and BA.The red area RA is an area in which the ratio of the first pixel dataR-data is relatively greater than that of the second and third pixeldata G-data and B-data, and the green area GA is an area in which theratio of the second pixel data G-data is relatively greater than that ofthe first and third pixel data R-data and B-data. In addition, the bluearea BA is an area in which the ratio of the third pixel data B-data isrelatively greater than that of the first and second pixel data R-dataand G-data.

As an example of the invention, when the red, green, and blue areas RA,GA, and BA are matched to a hue scale, the red area RA corresponds to anarea including a range from about 0 degree (°) to about 60° of the huescale and a range from about 300° to about 360° of the hue scale, thegreen area GA corresponds to an area including a range from about 60° toabout 180° of the hue scale, and the blue area BA corresponds to an areaincluding a range from about 180° to about 300° of the hue scale.

Although not shown in drawing figures, the hue data H-data may furtherinclude chroma information and brightness information generated based onthe grayscale level of the first, second, and third data R-data, G-data,and B-data in addition to the color information.

Referring back to FIG. 2, the comparing/determining unit 230 receivesthe hue data H-data from the converter 210 and compares the received huedata H-data to predetermined reference data Ref-data. In a case that thehue data H-data include only the color information, the reference dataRef-data include reference information on the color. However, in a casethat the hue data H-data include two or more information, such as thecolor information and the chroma information, the color information andthe brightness information, etc., the reference data Ref-data furtherinclude reference information on the chroma and the brightness.

In addition, the comparing/determining unit 230 may set a referencerange using two reference data Ref-data. In an exemplary embodiment, ina case that the two reference data Ref-data are respectively set to 0°and 120°, the reference range may be set to a range from 0° to 120°(refer to FIG. 3), for example.

The comparing/determining unit 230 determines whether the hue dataH-data exists in the reference range. According to the compared result,the comparing/determining unit 230 counts up the number of the hue dataH-data existing in the reference range. In an exemplary embodiment, thecomparing/determining unit 230 may count up the number of the hue dataH-data existing in the reference range among the hue data H-datagenerated based on data of one frame, for example.

In the above descriptions, one reference range is set in thecomparing/determining unit 230 as an example, but the number of thereference ranges should not be limited to one. That is, according toanother exemplary embodiment, two or more reference ranges may be set inthe comparing/determining unit 230. In another exemplary embodiment, anarea from 0° to 120° may be set to a first reference range, and an areafrom 240° to 300° may be set to a second reference range, for example.In this case, the comparing/determining unit 230 may count up the numberof the hue-data existing in each of the first and second referenceranges.

The comparing/determining unit 230 provides the counted result value,i.e., a counted value C-value, to the outputting unit 250. In the casethat one reference range is set, the comparing/determining unit 230outputs one counted value. However, in the case that two or morereference ranges are set, the comparing/determining unit 230 may outputcounted values respectively corresponding to the reference ranges.

The outputting unit 250 compares the counted value C-value to thepredetermined reference value Ref-value. According to the comparedresult, in a case that the counted value C-value is equal to or greaterthan the reference value Ref-value, the outputting unit 250 may outputthe frequency control signal F-con to change the driving frequency.

In the case that the number of the reference ranges is one, onereference value Ref-value is set in the outputting unit 250, but in thecase that the number of the reference ranges is two or more, differentreference values Ref-value from each other may be set in the outputtingunit 250 to respectively correspond to the reference ranges. Inaddition, outputting unit 250 may output different frequency controlsignals from each other to change the driving frequency to differentcompensation frequencies from each other depending on each of thereference ranges.

In an exemplary embodiment, in a case that the counted value C-value ofthe hue data H-data existing in the first reference range from 60° to120° is greater than the reference value Ref-value (i.e., a first case),the driving frequency may be changed to a first compensation frequency,for example. In addition, in a case that the counted value C-value ofthe hue data H-data existing in the second reference range from 240° to300° is greater than the reference value Ref-value (i.e., a secondcase), the driving frequency may be changed to a second compensationfrequency. When both of the first case and the second case occur, thedriving frequency may be changed to an average value of the first andsecond compensation frequencies.

FIG. 4 is a view showing a normal driving period and a compensationdriving period.

Here, the normal driving period corresponds to a period in which thedisplay 100 (refer to FIG. 1) is driven at the driving frequency F1 setin the display apparatus 500 (refer to FIG. 1), and the compensationdriving period corresponds to a period in which the display 100 isdriven at the compensation frequency F2.

Referring to FIG. 4, in an exemplary embodiment, the driving frequencyF1 is about 60 Hertz (Hz), and the compensation frequency F2 is about 48Hz, for example. The driving frequency F1 and the compensation frequencyF2 should not be limited thereto or thereby.

The display 100 is driven at 60 Hz during the normal driving period.Accordingly, 60 frames are displayed during a period of about a second,and a period in which one frame is displayed is about 16.7 milliseconds(ms). The display 100 is driven at a frequency lower than 60 Hz, e.g.,at 48 Hz during the compensation driving period. Accordingly, 48 framesare displayed during a period of about a second, and a period in whichone frame is displayed is about 20.83 ms.

As described above, when the frequency at which the display 100 isdriven is reduced to about 48 Hz from about 60 Hz, the time desired todisplay one frame increases, and the charging time of each of the pixelsincreases. As a result, the color non-uniformity caused by theinsufficient of the charge rate may be improved.

FIG. 5 is a view showing a transition period between the normal drivingperiod and the compensation driving period.

Referring to FIG. 5, the transition period may be further definedbetween the normal driving period and the compensation driving period asanother example of the invention. For the convenience of explanation, atime for the transition period is set to two seconds in FIG. 5, but itshould not be limited to two seconds.

The transition period is provided to allow the frequency to be changedstepwise to the compensation frequency F2 of the compensation drivingperiod from the driving frequency F1 of the normal driving period. Thatis, the driving frequency F1 of the normal driving period is reducedstepwise to the compensation frequency F2 of the compensation drivingperiod during the transition period. As an example, the transitionperiod may be divided into a period in which the display 100 is drivenat 56 Hz and a period in which the display 100 is driven at 52 Hz.

In FIG. 5, the frequency is changed in two steps during the transitionperiod, but it should not be limited thereto or thereby. That is, thefrequency may be changed in one step or three or more steps during thetransition period.

FIG. 6 is a block diagram showing a display apparatus 505 according toanother exemplary embodiment of the invention. In FIG. 6, the samereference numerals denote the same elements in FIG. 1, and thus thedetailed descriptions of the same elements will be omitted.

Referring to FIG. 6, the display apparatus 505 may further include anoptical characteristic compensator 350. In FIG. 6, the display 100 isomitted, but the display apparatus 505 includes the display 100.

As an example, the optical characteristic compensator 350 may bedisposed between the frequency adjuster 300 and the driver 400. Theoptical characteristic compensator 350 receives the image data Video(F2)in synchronization with the compensation frequency F2 and compensatesfor the optical characteristic of the image data Video(F2) to apply thecompensated image data Video′(F2) to the driver 400.

The optical characteristic compensator 350 is desired to haveinformation on the compensation frequency F2 such that the opticalcharacteristic of the image data Video(F2) is compensated correspondingto the compensation frequency F2. Accordingly, the opticalcharacteristic compensator 350 may receive the frequency control signalF-con from the frequency compensator 200. According to another exemplaryembodiment, the optical characteristic compensator 350 may receive aseparate control signal including information on the compensationfrequency F2 from the frequency adjuster 300.

The driver 400 receives the compensated image data Video′(F2) andprocesses the compensated image data Video′(F2) to generate the datasignals D1 to Dm. Accordingly, the display 100 (refer to FIG. 1) mayprevent the optical characteristic from varying when the frequency ischanged to the compensation frequency F2 by the optical characteristiccompensator 350.

In FIG. 6, the optical characteristic compensator 350 is disposedbetween the frequency adjuster 300 and the driver 400 as a separateunit, but it should not be limited thereto or thereby. That is,according to another exemplary embodiment, the optical characteristiccompensator 350 may be included in one of the frequency adjuster 300 andthe driver 400.

FIG. 7 is a block diagram showing the optical characteristic compensator350 shown in FIG. 6.

Referring to FIG. 7, the optical characteristic compensator 350 includesa selector 351, first and second look-up tables F1-LUT and F2-LUT, and acompensator 353. The selector 351 receives the frequency control signalF-con and selects a look-up table corresponding to the frequency amongthe first and second look-up tables F1-LUT and F2-LUT in response to thefrequency control signal F-con.

In a case that the frequency control signal F-con includes informationthat the driving frequency F1 is changed to the compensation frequencyF2, the selector 351 may output a selection signal Sel1 to select thesecond look-up table F2-LUT among the first and second look-up tablesF1-LUT and F2-LUT. Accordingly, the compensator 353 compensates for theimage data Video(F2) with reference to the second look-up table F2-LUTin response to the selection signal Sel1, and then outputs thecompensated image data Video′(F2).

Although not shown in FIG. 7, the frequency control signal F-con mayinclude information to maintain the driving frequency F1 or to restoreto the driving frequency F1 from the compensation frequency F2. In thesecases, the selector 351 may output a selection signal Sel2 to select thefirst look-up table F1-LUT among the first and second look-up tablesF1-LUT and F2-LUT.

The compensator 353 may receive the image data Video(F1) synchronizedwith the driving frequency F1 from the frequency adjuster 300.Accordingly, the compensator 353 compensates for the image dataVideo(F1) with reference to the first look-up table F1-LUT in responseto the selection signal Sel2 and outputs the compensated image dataVideo′(F1).

FIG. 7 shows the optical characteristic compensator 350 corresponding tothe exemplary embodiment of FIG. 4 in which the transition period is notdefined between the normal driving period and the compensation drivingperiod. However, in the case that the transition period is definedbetween the normal driving period and the compensation driving period asshown in FIG. 5, a configuration of the optical characteristiccompensator 350 may be changed. That is, in the case that the frequencyis changed stepwise during the transition period, the opticalcharacteristic compensator 350 may further include a look-up tablecorresponding to a corresponding frequency, and the compensator 353 maycompensate for the image data by taking into account the correspondingfrequency.

FIG. 8 is a block diagram showing an optical characteristic compensator355 according to another exemplary embodiment of the invention.

FIG. 8 shows an example of the optical characteristic compensator 355designed to correspond to the structure in which the frequency ischanged in two steps during the transition period.

The display 100 (refer to FIG. 1) may be driven at a first transitionfrequency Fi1 during a former transition period of the transition periodand driven at a second transition frequency Fi2 during a lattertransition period of the transition period. In this case, the opticalcharacteristic compensator 355 may further include a third look-up tableFi1-LUT corresponding to the first transition frequency Fi1 and a fourthlook-up table Fi2-LUT corresponding to the second transition frequencyFi2.

Accordingly, the selector 351 may further receive a control signal I-conincluding information on the transition period and the first and secondtransition frequencies Fi1 and Fi2 in addition to the frequency controlsignal F-con.

The selector 351 may output a selection signal Sel3 to select the thirdlook-up table Fi1-LUT of the third and fourth look-up tables Fi1-LUT andFi2-LUT during the former transition period. Although not shown in FIG.8, the frequency adjuster 300 (refer to FIG. 6) changes the drivingfrequency to the first transition frequency Fi1 and converts the imagedata Video(F1) and the image control signal Con(F1) to signalssynchronized with the first transition frequency Fi1 to output thesignals synchronized with the first transition frequency Fi1.

Accordingly, the compensator 353 may receive the image data Video(Fi1)synchronized with the first transition frequency Fi1 from the frequencyadjuster 300 during the former transition period. The compensator 353compensates for the image data Video(Fi1) in response to the selectionsignal Sel3 with reference to the third look-up table Fi1-LUT andoutputs the compensated image data Video′(Fi1).

Although not shown in FIG. 8, the frequency adjuster 300 changes thedriving frequency to the second transition frequency Fi2 and convertsthe image data Video(F1) and the image control signal Con(F1) to signalssynchronized with the second transition frequency Fi2 to output thesignals synchronized with the second transition frequency Fi2.

Accordingly, the compensator 353 may receive the image data Video(Fi2)synchronized with the second transition frequency Fi2 from the frequencyadjuster 300 during the latter transition period. The compensator 353compensates for the image data Video(Fi2) in response to the selectionsignal Sel4 with reference to the fourth look-up table Fi2-LUT andoutputs the compensated image data Video′(Fi2).

FIG. 9 is a schematic view showing a display apparatus 550 according toan exemplary embodiment of the invention.

Referring to FIG. 9, the display apparatus 550 includes a main board 510and a display board 520.

The main board 510 may provide an interface to connect the displayapparatus 550 to external peripheral devices (not shown). Accordingly,the main board 510 receives various control signals and image signalsfrom the external peripheral devices to drive the display 100 (refer toFIG. 1).

The display board 520 is connected to the main board 510 to receive thevarious control signals and the image signals. The display board 520includes various circuits to convert the signals received through themain board 510 to control signals desired to drive the display 100 andimage signals appropriate to drive the display 100.

As an example, the frequency adjuster 300 may be included in the mainboard 510, and the frequency compensator 200 and the opticalcharacteristic compensator 350 may be included in the display board 520.

In FIG. 9, the driver 400 is included in the display board 520. However,according to another exemplary embodiment, some circuits, e.g., thetiming controller, of circuits of the driver 400 may be included in thedisplay board 520. In this case, the other circuits, e.g., the datadriver, the gate driver, etc., of the driver 400 may be mounted (e.g.,disposed) on the liquid crystal panel of the display 100 in anintegrated circuit (IC) form or built-in in the liquid crystal panel.

FIG. 10 is a schematic view showing a display apparatus 570 according toanother exemplary embodiment of the invention.

Referring to FIG. 10, the display apparatus 570 includes a frequencycompensator 200, frequency adjuster 300, an optical characteristiccompensator 350, and a driver 400. The frequency compensator 200, thefrequency adjuster 300, and the optical characteristic compensator 350may be disposed in a main board 510 of the display apparatus 570, andthe driver 400 may be disposed in a display board 520 of the displayapparatus 570.

Different from those structures shown in FIGS. 9 and 10, a structure inwhich the frequency compensator 200, the frequency adjuster 300, theoptical characteristic compensator 350, and the driver 400 are disposedin the display board 520 may be implemented.

In addition, according to another exemplary embodiment, a structure inwhich the frequency compensator 200 is disposed in the main board 510and the frequency adjuster 300, the optical characteristic compensator350, and the driver 400 are disposed in the display board 520 may beimplemented.

Further, positions of the frequency compensator 200, the frequencyadjuster 300, the optical characteristic compensator 350, and the driver400 may be changed as needed when the display apparatus is designed.

Although the exemplary embodiments of the invention have been described,it is understood that the invention should not be limited to theseexemplary embodiments but various changes and modifications may be madeby one ordinary skilled in the art within the spirit and scope of theinvention as hereinafter claimed.

What is claimed is:
 1. A display apparatus comprising: a displaycomprising first, second, and third pixels to display an imagecomprising color information; a frequency compensator which receivesfirst, second, and third pixel data respectively corresponding to thefirst, second, and third pixels, converting the first, second, and thirdpixel data to hue data, and outputs a frequency control signal to changea current driving frequency (hereinafter, referred to as a drivingfrequency) of the display based on the hue data; a frequency adjusterwhich changes the driving frequency to a predetermined compensationfrequency in response to the frequency control signal and changes afrequency of image data and an image control signal to output thechanged image data and the changed image control signal such that thedisplay is driven at the predetermined compensation frequency; and adriver which receives the changed image data and the changed imagecontrol signal and drives the display at the predetermined compensationfrequency.
 2. The display apparatus of claim 1, wherein the frequencycompensator comprises: a converter which converts the first, second, andthird pixel data to the hue data; a comparing/determining unit whichcompares the hue data to predetermined reference data and counts up anumber of the hue data greater than the predetermined reference data;and an outputting unit which outputs the frequency control signalincluding a first information to change the driving frequency when thecounted value is equal to or greater than a predetermined referencevalue.
 3. The display apparatus of claim 2, wherein, when the countedvalue is equal to or greater than the predetermined reference value, theoutputting unit outputs the frequency control signal to decrease thedriving frequency, and the frequency adjuster changes the drivingfrequency to the predetermined compensation frequency smaller than thedriving frequency in response to the frequency control signal.
 4. Thedisplay apparatus of claim 3, wherein the frequency adjuster changes thefrequency of the image data and the image control signal such that thedisplay is driven at a transition frequency during a predeterminedtransition period before changing the driving frequency to thepredetermined compensation frequency and outputs the changed image dataand the image control signal.
 5. The display apparatus of claim 4,wherein the transition frequency is greater than the predeterminedcompensation frequency and smaller than the driving frequency.
 6. Thedisplay apparatus of claim 2, wherein, when the counted value is equalto or smaller than the predetermined reference value, the outputtingunit outputs the frequency control signal including a second informationto maintain the driving frequency, and the frequency adjuster maintainsthe driving frequency in response to the frequency control signal. 7.The display apparatus of claim 2, wherein the display comprises aplurality of unit pixels, each of the plurality of unit pixels comprisesthe first, second, and third pixels, and the first, second, and thirdpixel data are red, green, and blue pixel data, respectively.
 8. Thedisplay apparatus of claim 2, wherein the hue data are data within firstto third hue scale ranges, and the predetermined reference data are setto one or more in each of the first to third hue scale ranges.
 9. Thedisplay apparatus of claim 8, wherein each of the first to third huescale ranges is divided into a predetermined number of reference ranges,and the predetermined reference data are set in every reference range.10. The display apparatus of claim 9, wherein the comparing/determiningunit determines which section the hue data are located in among thereference sections and compares the hue data to the predeterminedreference data set in a corresponding reference range among thereference ranges.
 11. The display apparatus of claim 8, whereinreference frequencies set in the reference ranges have differentfrequencies from each other.
 12. The display apparatus of claim 1,further comprising an optical characteristic compensator whichcompensates for an optical characteristic of the changed image data. 13.The display apparatus of claim 12, wherein the optical characteristiccompensator is disposed between the frequency adjuster and the driver toapply the compensated image data to the driver.
 14. The displayapparatus of claim 12, wherein the optical characteristic compensatorcomprises a look-up table that stores a compensation value correspondingto the predetermined compensation frequency, and the opticalcharacteristic compensator compensates for the changed image data basedon the compensation value.
 15. The display apparatus of claim 1, furthercomprising: a main board which receives and processes various controlsignals and image signals from an external peripheral device; and adisplay board connected to the main board and comprising a circuit usedto drive the display.
 16. The display apparatus of claim 15, wherein thefrequency adjuster is disposed in the main board, and the frequencycompensator and the driver are disposed in the display board.
 17. Thedisplay apparatus of claim 15, wherein the frequency compensator and thefrequency adjuster are disposed in the main board, and the driver isdisposed in the display board.
 18. A method of driving a displayapparatus comprising a display comprising first, second, and thirdpixels to display an image having color information, the methodcomprising: receiving first, second, and third pixel data respectivelycorresponding to the first, second, and third pixels to convert thefirst, second, and third data to hue data; outputting a frequencycontrol signal to change a current driving frequency of the displaybased on the hue data; changing the current driving frequency to apredetermined compensation frequency in response to the frequencycontrol signal and changing a frequency of image data and an imagecontrol signal to output the changed image data and the changed imagecontrol signal such that the display is driven at the predeterminedcompensation frequency; and receiving the changed image data and thechanged image control signal to drive the display at the predeterminedcompensation frequency.
 19. The method of claim 18, wherein theoutputting the frequency control signal comprises: comparing the huedata to predetermined reference data to count up a number of the huedata greater than the predetermined reference data; and outputting thefrequency control signal to change the current driving frequency whenthe counted value is equal to or greater than a predetermined referencevalue.
 20. The method of claim 19, wherein, when the counted value isequal to or greater than the reference value, the frequency controlsignal is outputted to decrease the current driving frequency.